Fusible strut for automatic sprinklers



June 30, 1942. w. B. GRIIFFITH 2,287,983

FUSIBLE STRUT FOR AUTOMATIC SPRINKLERS Filed July 26, 1940 Patented June30, 1942 FUSIBLE STRUT FOR. AUTOMATIC SPRINKLEB S William 13.. Grifiith,Audubon' N. J. Application July-26, 1940, Serial No. 347.657

5 Claims. (01.1 169-j-38) This invention relates to improvements infusible struts used in connection with sprinklers for sprinkler systemsfor fire protection.

The object of my invention is to construct a strut comprising twomembers mounted in axial alignment for giving them rigidity againstlateral strains and also for permitting free axial movement. I

A further object is to provide a strut comprisin telescoping members,and a fusible element for holding said members in extended relation, andarrange said element for separating the exposed adjacent surfaces ofsaid members sufiiciently to prevent them from permanently uniting dueto corrosion.

A further object is to provide a washer formed of fusible material; saidwasher having a thick central portion and a relatively-thin peripheralportion, arranged so that said thick portion will withstand thecompression strains applied to said members, and to provide the memberswith recesses which are occupied by said thickportion of the washer.

A further object is to construct said members with walls defining saidrecesses and arrange the walls for compressing the thick central portionof the washer toward the axis of the strut members and thereby reducingthe tendency of the material to extrude from between said members whenthey are held under compression.

These together with variousother-novel features of construction andarrangement of the parts, which will be more fully hereinafter describedand claimed, constitute my invention.

Referring to the accompanying drawing:

Fig. 1 is a vertical sectional view of an automatic sprinkler embodyingmy novel strut.

Fig. 2 is a central longitudinal section of a strut detached, showing amodification of my invention.

In the drawing in which like reference characters refer to like parts, 5represents a sprinkler of the type disclosed in Letters Patent No.2,165,477, issued to me July 11, 1939.

The sprinkler 5 comprises a body 6 having a screw thread 1 forconnecting the sprinkler with a distributing pipe of a sprinkler system,not shown in the drawing. The body 6 has an outlet passage which isclosed by valve 10. A frame l2 upon the body carries an adjustableabutment l3. Separable struts l5 and I6 normally hold the valve lclosed. The strut l consists of a split ring mounted on the valve In.The strut I6 is in the form of a lever having abearing head I1 pivotallymounted upon the adjacent ends of 55 33 extends into and fills saidrecess 30.

the split ring l5 and engaged-by the screw [3 whichtends to swing theopposite end of the strut into engagement with the side face of the ringfor holding the valve closed. In the. event of a fire-the strut l6 willswing through the ring l5 and said struts will fall from the frame l2and allow the valve- [0 to open in the usual manner.

The novel strut lficomprisestwo members [8 and I9 telescopicallymounted;The member 18 is in the form of a cylinder, or rod; having'an axial bore20, open-at the end oppositeto the bearing head IL The open end of thebore is surrounded by an annular flange 2|.

The member I!) of the strut l6 comprises a shaft 23 having a sliding fitin said bore 20. A flange 24 is formed upon the outer end of-the shaft23 and isadapted to abut against the flange 2| whenthe-shaft is movedinto said 'bore. The member [9': is provided upon its extreme. outerportion with a conical lug, or head25, adapted for engagementwith thelateral face of the ring strut l5. Said member [9 has the shaft portion23 formed-of sufficient length to provide a rigid bearing between themembers [8 and IQ for holding them in alignment when subjected to alateral thrust, as when forced into engagement with the sideface ofthering l 5 by the action of the abutmentscrewfl3. This constructionalso provides for the free axial movement of said members [8 and 19.

A disk or washer 26, formed of soft solder, or other fusible material,is interposed between the annular 'abutting'fiange surfaces of themembers l8 and l9. Said washer 26 is adapted for holding the members l3and IS in extended relation for locking engagement with the ring I5.When the washer 26 is fused, in the event of fire, the members l8 and I9will telescope sufficiently to allow the strut Hi to swing through thering 15. The washer 26 has an axial aperture through which the shaft l9extends, and the outer diameter of the washer corresponds to thediameter of the flanges 2| and 24.

Figs. 1 and 2 illustrate forms of my invention constructed forfurtherreducing the tendency of the fusible material of the washer to extrudefrom between the members of the strut.

The strut member [8, shown in Fig. 2, is provided with an axial recessor counterbore 30, which is defined by a conical wall 3|.

F g. 2 shows a fusible washer 32 hav ng an axial protuberance 33 whichgives thecentral portion of the washer a relatively thicker body thanthe periphery of the washer. Said protuberance The thicker body portion33 of the washer is confined within said recess 30 by the Walls 3| whichare inclined in a direction for compressing the body portion of thewasher toward the axis of the strut. By this construction the thickaxial portion of the washer presents a greater resistance to a forcetending to move the flanges 35 and 36 into abutting engagement andreduces the tendency of the material of the exposed annular portion ofthe washer from extruding between the spaced flanges 35 and 36.

The resistance of the washer 32 against compression is further increasedby providing the flanged head 38 of the member I9 with a recess 40,which is similar in construction to the recess 30 formed in the member18. The washer 32 is also provided with a second protuberance 4| adaptedto enter and fill the recess 48.

Fig. 1 shows a construction of the members 18 and [9 in which the axialrecesses 44 and 45 are formed by cylindrical walls 46 and annular bottomWalls 41, forming a series of recesses of different depths arranged instep formation and adapted for confining the fusible material, ofwhichthe washer 26 is formed, from extruding from the members of thestrut. The Washer 23 is provided with enlarged axial portions 5! and 52,adapted to occupy the recesses 44 and 45 and take the compression towhich the strut members are subjected.

The operation of the device is as follows: The members l8 and 19 of mynovel strut are held in extended position for locking engagement withthe ring strut l5, by the fusible washer, which has a thickness inexcess of the distance the members l8 and I9 must be contracted to passthrough the ring [5. When the material forming the washer is fused itflows from the members l8 and I9 and allows the shaft 23 to be movedinto the bore of the member l8, so that the strut l6 will swing throughthe ring and release the valve l0.

The failure of struts to operate due to corrosion, is eliminated by thewasher forming a'seal for excluding the atmosphere from the slidingsurfaces of the shaft l9 and the bore of the cylinder l8. The peripheryof the Washer has sulficient thickness to prevent corrosion between theexposed metal surfaces of the adjacent flanges of the members 18 and I9.

The washers 26 and 32 shown in Figs. 1 and 2, are provided withrelatively thicker axial portions adapted for reducing the compressionupon the peripheral portions of the washers, so that the soft materialof which the washers are formed will not extrude from the strut membersat the ordinary temperature. By this construction the washers may beformed of material which will fuse at a low temperature, thus making thestrut very sensitive in operation.

I claim:

1. An automatic sprinkler having separable struts, one of said strutscomprising telescoping members, annular abutting surfaces upon saidmembers adapted to engage when said members are in contracted relation,a washer formed of fusible material positioned between said surfaces forholding said members in extended relation, said washer having a centralportion which is relatively thicker than its peripheral portion, and oneof said members having an axial recess formed therein adapted to beoccupied by said thicker portion of the washer.

2. A fusible strut comprising a rod having an axial bore, a shaftslidably mounted in said bore, enlarged flanges upon said rod and saidshaft adapted to abut when the shaft is moved into said bore, a washerformed of fusible material positioned between said flanges; one of saidflanges having axial counterbores extending to different depths thereinand arranged in step formation, and an axial protuberance upon saidwasher adapted to occupy said bores.

3. A fusible strut comprising a rod having an axial bore, a shaftslidably mounted in said bore, an enlarged head upon the outer end ofsaid shaft, a washer formed of fusible material, said washer having aperipheral portion located between the head and the end of the rod, saidWasher having an axial portion which is relatively thicker than itsperipheral portion, and said rod having an axial counterbore adapted tobe occupied by said thicker portion of the washer.

4. A fusible strut comprising arod having an axial bore, a shaftslidably mounted in said bore, an enlarged head upon the outer end ofsaid shaft, a washer formed of fusible material, said washer having aperipheral portion located between the head and the end of the rod, saidwasher having an axial portion which is relatively thicker than itsperipheral portion, and

" said head having a recess surrounding said shaft and adapted to beoccupied by said thicker portion of the washer.

5. A fusible strut comprising a rod having an axial bore, a shaftslidably mounted in said bore, an enlarged head upon the outer end ofsaid shaft, a washer formed of fusible material, said washer having aperipheral portion positioned between said head and the end of the'rod,protuberances positioned axially upon opposite faces of the washer, andsaid rod and said head having axial recesses formed therein adapted tobe occupied by said protuberances.

WILLIAM B. GRIFFITH.

